Blasting Method Using a Control Device for Inducing a Blast Pressure, and Control Device for Inducing the Blast Pressure to Apply the Method

ABSTRACT

The present invention relates to a blasting method using a control device for inducing a blast pressure, and a control device for inducing the blast pressure to apply the method. According to the blasting method using the control device for inducing the blast pressure, when a blasting operation is performed at the outermost hole of a tunnel or a wayside or wall surface of a structure constructed at a location in which an adjacent structure of a downtown area is located, a transfer path of the blast pressure is controlled using the control device for inducing the blast pressure so that the blast pressure does not exceed a proposed blast line, but is limitedly transferred into only a blasting area. Thus, a smooth and elegant blasted surface may be secured, and simultaneously, an over-break may be prevented and vibration and noises may be minimized. According to the present invention, since a general inexpensive explosive is loaded into a blasting prevention cover and easily utilized, the general inexpensive explosive may be replaced with an existing expensive precision explosive to significantly reduce blasting costs and improve blasting efficiency, thereby having a large economic impact and useful effects.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2011-0014967, filed on Feb. 21, 2011 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an innovative blasting technique wherein at the time of blasting operation of outermost holes of a tunnel or road surface and wall surface and the like of a site where adjacent structures are positioned in a city, a transmission path of the blast pressure can be controlled in such a way that the blast pressure does not exceed a predetermined blast line by means of a blast pressure-guiding control device, but is limitedly transmitted only to a blast area, whereby more smooth and fine-looking blast surface is obtained and also overbreak can be prevented and vibration and noise can be minimized.

BACKGROUND ART

In general, construction work and engineering work are key industries of a nation, and the scale and number of the works are much increased with development of industry, and as a basic work for carrying out such construction work and engineering work, a blasting operation is one of operations which are most frequently done out in various construction sites (road construction, tunnel, a site where adjacent structures are positioned in a city and the like).

The blasting operation has a purpose of removing rocks, and a method for most simply removing the rocks generally consists in using of explosive. The explosive has an advantage that it is easily available and can be conveniently used.

As already known, general blasting method is a method in which circular blast holes are drilled and then the explosive is loaded in the center of the hole to be blasted, wherein since uniform blast pressure is applied to the whole hole walls of the blast holes, there are problems that, especially in constructing of a tunnel, cross section of the tunnel is not smooth and is uneven, blast vibration and noise are severe and thus the blast pressure exceeds the predetermined blast line of the tunnel, therefore the tunnel is further excavated, which results in occurrence of overbreak.

Therefore, for solving the above-mentioned problems, controlling of the blast pressure is a very important key point. Up to now, as such a method for controlling the blast pressure, there are proposed a method wherein position of free surface and interval between holes are properly adjusted, decoupling explosive loading method etc., however, these method have disadvantages that they cost a great deal and their control effects are not so high.

In particular, the decoupling explosive loading method is a blasting method wherein fine explosive is utilized which is most wide-spreadly much used, wherein crack is generated along the predetermined blast line by utilizing a phenomenon that range of destruction is decreased while impact effect of the explosive uniformly acting on the whole hole wall of the blast hole since air layer is formed between the explosive installed in the center of the blast hole and the hole wall of the blast hole.

However, in such a case, there is a problem that since the whole impact effect of the explosive is decreased, the inside of the predetermined blast hole (blast area) is subject to shortage of the blast pressure blast line on the contrary and thus underbreak is occurred, and it is the actual circumstances that there is provided an insignificant effect that only occurrence area of the overbreak is slightly decreased as compared to the existing blasting method.

DISCLOSURE OF THE INVENTION

The present invention has been devised to actively solve various problems involved in blasting method according to the prior art, and its object is to provide a blasting method and blast pressure-guiding control device wherein by loading the explosive in blast pressure-blocking covers which partially wrap only one side of the explosive along longitudinal direction thereof and thereafter inserting and installing the blast pressure-blocking covers in blast holes so as to face a predetermined blast line, transmission path of the blast pressure can be freely controlled in such a way that the blast pressure is not transmitted to the direction of the predetermined blast line by means of the blast pressure-blocking covers at the time of blasting operation, but is transmitted to a blast area, i.e., the other side of the predetermined blast line.

The present invention provides as means for achieving the above-mentioned object a blasting method comprising a step wherein the explosive is loaded in each of a plurality of blast pressure-blocking covers opened on one side thereof; a step wherein the blast pressure-blocking covers are longitudinally connected and assembled; a step wherein the plurality of connected and assembled blast pressure-blocking covers are inserted and installed in blast holes so as to face the predetermined blast line; a step wherein the tamping is charged in the blast holes; and a step wherein detonator leg line is integrally connected with blast mother line and thereafter the explosive is blasted.

Furthermore, the present invention provide a blast pressure-guiding control device wherein partially-opened blast pressure-guiding passage is formed on one side of the blast pressure-blocking cover of circular cross section, explosive-loading part is formed inside the blast pressure-guiding passage, and a second wall and third wall are successively and integrally formed on inner surface of the blast pressure-blocking cover, and cover-assembling means is provided which comprises a coupling projection protruding outwardly from the second wall on one longitudinal side thereof and a coupling groove formed recessed from the second wall on the other side thereof, whereby the blast pressure-blocking covers can be connected and assembled according to the number of the explosive.

According to the present invention, since the blast pressure-blocking covers partially wrapping only one side of the explosive are disposed in the blast holes so as to face the predetermined blast line, the blast pressure-blocking covers block transmission of the blast pressure to the predetermined blast line, thus the blast pressure cannot exceed the predetermined blast line at the time of blasting operation, but is limitedly transmitted only to a blast area, i.e., the inside of the predetermined blast line, whereby there are provided effects that blast surface is correctly formed along the predetermined blast line and the blast surface is more smooth and fine-looking, and overbreak can be effectively prevented and vibration and noise can be minimized, thus quality of construction work is drastically enhanced.

Furthermore, since existing high-priced fine explosive can be replaced by loading conventional low-priced explosive in the blast pressure-blocking covers and then conveniently using it, there is provided useful effect that blast efficiency is increased while blast cost is drastically reduced, thus economic ripple effect is very significant.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a longitudinal sectional view illustrating a state wherein a blast pressure-guiding control device according to an example of the present invention is installed in blast hole at the time of blasting operation of a tunnel.

FIG. 2 is a sectional view taken along line A-A of FIG. 1 of the present invention.

FIG. 3 is a front view of a blast pressure-blocking cover of the present invention.

FIG. 4 is an exploded perspective view of the blast pressure-blocking cover of present invention.

FIG. 5 is a top view illustrating a state wherein explosive is loaded in the blast pressure-blocking cover of present invention.

FIG. 6 is an enlarged sectional view illustrating a state wherein the blast pressure-blocking cover of present invention loaded with the explosive is installed in the blast hole.

FIG. 7 is an enlarged sectional view illustrating a state wherein the blast pressure-blocking covers of present invention are connected and assembled with each other.

FIG. 8 is a top view of a blast pressure-guiding control device according to another example of present invention.

FIG. 9 is a top view of a blast pressure-guiding control device according to yet another example of present invention.

FIG. 10 is a block diagram showing sequence of the blasting method according to the present invention.

list of reference numerals 1: explosive 2: blast hole 4: predetermined blast line 5: detonator leg line 6: gap 100, 100a, 100b: blast pressure- guiding control device 110: blast pressure-blocking cover 111: blast pressure-guiding passage 112: explosive-loading part 113, 123, 133: buffering projection 115: connecting band 120: second wall 125, 135: air layer 130: third wall 140: cover-assembling means 141: coupling projection 142: coupling groove 143: inclined surface 144: lock 145: locking hole

MODES FOR CARRYING OUT THE INVENTION

Preferred examples for embodying means for achieving the object of the present invention will be described.

Brief description is as follows about a blasting method using blast pressure-guiding control device according to preferred examples of the present invention. The blasting method comprises explosive-loading step (S10) wherein the explosive (1) is loaded in each of a plurality of blast pressure-blocking covers (110) formed with a blast pressure-guiding passage (11) therein and thereafter the explosive (1) is fixed by wrapping it with connecting bands (115); cover-assembling step (S20) wherein the plurality of blast pressure-blocking covers (110) are longitudinally connected and assembled; cover-installing step (S30) wherein the plurality of blast pressure-blocking covers (110) thus connected and assembled are inserted and installed in blast holes (2) so as to face a predetermined blast line (4); tamping-charging step (S40) wherein the tamping (7) is charged in the blast holes (2); and detonator leg line-connecting and blasting step (S50) wherein the detonator leg line (5) is integrally connected with blast mother line and thereafter the explosive (1) is blasted.

In the following, for easily carrying out the present invention comprising the steps as briefly described above, each of the steps will be described in more detail.

Explosive-Loading Step (S10)

Firstly, in the present invention, the explosive (1) is loaded in each of the plurality of blast pressure-blocking covers (110) formed with the blast pressure-guiding passage (111) along its longitudinal direction on its one side.

That is, the explosive (1) is pushed and loaded into an explosive-loading part (112) formed inside the blast pressure-blocking covers (110), as illustrated in FIG. 5, and thereafter, the explosive (1) is firmly fixed by wrapping the explosive with the connecting bands (115) such that any play is not occurred.

At this point, since the blast pressure-blocking cover (110) is formed with the blast pressure-guiding passage (111) open on one side of the cover, tension is ensured which allows both end portions of the blast pressure-blocking cover to freely play upward and downward from the blast pressure-guiding passage (111) in the plane of the drawing, as seen in FIG. 5, whereby an effect is provided that various explosives (1) can be more smoothly loaded regardless of the size, form and type of the explosive (1).

Furthermore, the blast pressure-blocking cover (110) are formed having the same length as that of the explosive (1)) and thus one explosive (1) is can be loaded in one blast pressure-blocking cover (110), and in accordance with the amount used of the explosive (1) the corresponding number of the blast pressure-blocking covers (110) is used.

2) Cover-Assembling Step (S20)

A coupling projection (141) formed at one longitudinal side of the blast pressure-blocking cover (110) is fitted into a coupling groove (142) formed in another blast pressure-blocking cover (110), as seen in FIG. 7, such that the plurality of blast pressure-blocking covers (110) with the explosive (1) loaded at ratio of 1:1 can remain integrated with each other, whereby the blast pressure-blocking covers (110) with the explosive (1) loaded can be successively and integrally connected.

Therefore, since the blast pressure-blocking covers (110) can remain integrated with each other and the explosives (1) can also remain in longitudinally and integrally connected state, even if blast is occurred by connecting the detonator to any one of the explosives (1), the explosives (1) can be wholly blasted together.

3) Cover-Installing Step (S30)

If the connecting and assembling of the blast pressure-blocking covers (110) is completed, the plurality of the blast pressure-blocking covers (110) connected and assembled are inserted and installed in the blast hole (2) in the state of the detonator leg line (5) connected to one of the explosives (1) being exposed to the outside of the blast hole (2).

At this point, for controlling the blast pressure to be limitedly transmitted only to the inside of the predetermined blast line (4), not exceeding the line at the time of blasting operation of a tunnel (3) as shown in FIG. 1, the blast pressure-blocking covers (110) should be necessarily inserted and installed in the blast holes (2) so as to face the predetermined blast line (4).

That is, by disposing the blast pressure-blocking covers (110) so as to face the predetermined blast line (4), the predetermined blast line (4) and the explosive (1) are kept apart from each other with the blast pressure-blocking cover (110) being present therebetween, whereby the blast pressure-blocking cover (110) prevent the blast pressure from exceeding the predetermined blast line (4) at the time of blasting operation, thereby forming smooth and fine-looking blast surface correctly along the predetermined blast line (4) and efficiently preventing the occurrence of overbreak and also reducing vibration and noise.

At the same time, since the blast pressure is smoothly guided and concentrated to the desired blast area through the blast pressure-guiding passage (11) formed in the blast pressure-blocking cover (110), there is provided an effect that underbreak does not occur.

In addition, buffering projections (113) formed on outer circumferential surface of the blast pressure-blocking cover (110), perform a buffering function when bumped against hole wall of the blast hole (2) at the time of blast, thereby more efficiently blocking transmission of the blast pressure to the predetermined blast line (4).

Meanwhile, with conventional detonator connected to a tip of the detonator leg line (5) being integrally connected with the explosive (1) loaded in a centrally-located blast pressure-blocking cover (110) of the plurality of the connected and assembled blast pressure-blocking covers (110), the detonator leg line (5) is exposed long to the outside while running along a gap (6) formed between inner surface of the blast pressure-blocking cover (110) and the explosive (1), whereby the detonator leg line (5) can be conveniently exposed to the outside of the blast hole (2) at the time of installing operation of the blast pressure-blocking covers (110).

4) Tamping-Charging Step (S40)

After the blast pressure-blocking covers (110) loaded with the explosive (1) is completely installed, the tamping (7) such as sand or clay etc. is charged in the blast hole (2) such that the explosive (1) can fully exhibit its power by means of sealing effect and at the same time noise and scattering can be prevented.

5) Detonator Leg Line-Connecting and Blasting Step (S50)

If charging of the tamping (7) is completed, the detonator leg line (5) exposed from the blast hole (2) to the outside is electrically and integrally connected with the blast mother line.

Then, electric current is supplied to the detonator from a remote location by using blast operator connected with the blast mother line, thereby blasting the explosive (1).

Meanwhile, the following description is about technical construction of a blast pressure-guiding control device (100) applied to the blasting method of the present invention.

Firstly, as shown in FIGS. 3 to 7, the blast pressure-guiding control device (100) of the present invention comprises a plurality of blast pressure-blocking covers (110) formed with an explosive-loading part (112) inside the blast pressure-guiding passage (111) formed on one side of the cover, a second wall (120) and third wall (130) of curved surface form successively and integrally formed on inner side of the blast pressure-blocking covers (110); and a cover-assembling means (140) enabling the plurality of blast pressure-blocking covers (110) to be longitudinally and integrally connected and assembled with each other.

Such a blast pressure-blocking covers (110) are formed having the same length as that of conventional explosive (1) so as to load the explosive (I) at the ratio of 1:1, and is made in a circular form in cross section so as to wrap a part of the explosive (1), with the blast pressure-guiding passage (111) formed partially open on one side of the cover along the longitudinal direction thereof, and the explosive-loading part (112) for loading the explosive (1) is formed inside the blast pressure-guiding passage (111).

At this point, the plurality of buffering projections (113) are protrudingly and equidistantly formed on the outer circumferential surface of the blast pressure-blocking cover (110), and perform a buffering function when the blast pressure-blocking cover (110) is bumped against the hole wall of the blast hole (2), thereby further increasing an effect of blocking transmission of the blast pressure to the predetermined blast line (4).

Furthermore, since the second wall (120) and third wall (130) of curved surface form are successively and integrally formed on inner side of the blast pressure-blocking cover (110), it is possible to doubly and triply block the transmission of the blast pressure to the predetermined blast line (4) and at the same to control transmission path of the blast pressure in such a way that the blast pressure is more concentratively transmitted to the direction of the blast pressure-guiding passage (111).

In addition, a plurality of buffering projections (123) and (133) are equidistantly formed on outer circumferential surfaces of the second wall (120) and third wall (130), as seen in FIG. 6, to perform a buffering function at the time of blast, and air layers (125) and (135) are formed between the buffering projections (123) and between the buffering projections (133), respectively, whereby the air layers serve as airbag at the time of blasting operation to absorb shocks, thereby more efficiently blocking the transmission of the blast pressure to unwanted direction, i.e., the predetermined blast line (4).

Meanwhile, for the construction of the cover-assembling means (140) which enables the plurality of blast pressure-blocking covers (110) to be longitudinally and integrally connected and assembled with each other, the coupling projection (141) is protrudingly formed integrally with the second wall (120) on one longitudinal side thereof, extending outwardly therefrom, and the coupling groove (142) is formed recessed inwardly from the second wall (120) on the other side thereof, whereby it is possible to quickly, conveniently and selectively connect and assemble several blast pressure-blocking covers (110) for its use according to the amount used of the explosive (1) by fitting the coupling projection (141) into the coupling groove (142) of the another blast pressure-blocking cover (110).

Here, a lock (144) with a inclined surface (143) is additionally and protrudingly formed on a tip of inner surface of the coupling projection (141). The lock (144) is fittedly coupled with a locking hole (145) formed through the third wall (130) while being connected with the coupling groove (142), thereby setting a locking, whereby it is possible to keep firmer and integrated connection and assembly state.

Furthermore, one end portion of the connecting band (115) for fixing the explosive (1) by wrapping the same is integrally fixed on one side of the outer circumferential surface of the blast pressure-blocking cover (110), and adhesive is applied on the other end portion of the connecting band (115), and an release paper (116) is attached on a surface on which the adhesive is applied.

Therefore, after the explosive (1) is loaded in the blast pressure-blocking cover (110) at the ratio of 1:1, if the connection band (115) is attached on the outer circumferential surface of the blast pressure-blocking cover (110) by removing the release paper (116), while the explosive (1) is wrapped by the connection band (115), the explosive (1) can be kept in integrated firm loaded state without being separated from the blast pressure-blocking cover (110).

After the explosive (1) is loaded in each of the blast pressure-blocking covers (110), as described above, the plurality of blast pressure-blocking covers (110) are longitudinally connected and assembled, however, there is no need to firstly perform loading operation of the explosive (1) and subsequently perform assembling operation of the blast pressure-blocking covers (110), so sequence of the operations may be changed, therefore, the only change of the sequence does not depart from the scope of the present invention.

Furthermore, for the present invention, when inserting and installing the plurality of connected and assembled, blast pressure-blocking covers (110) in the blast holes (2), the blast pressure-blocking covers (110) should be inserted and installed so as to face the predetermined blast line (4) as seen in FIG. 6.

That is, only when the blast pressure-blocking covers (110) are disposed so as to face the predetermined blast line (4), the blast pressure-blocking covers (110) perform a role of blocking the blast pressure so as not to be transmitted to the predetermined blast line (4) at the time of blasting of the explosive (1), thus not only can very smooth blast surface be obtained but overbreak can be effectively prevented as well, whereby there are provided effects that quality of construction work is drastically enhanced and vibration and noise can be minimized.

In addition, at the same time, since the blast pressure is smoothly guided toward the blast pressure-guiding passage (111) formed partially open, most of the blast pressure is transmitted to the direction of the inside of the predetermined blast line (4), i.e., a blast area where the blast will be actually occurred, whereby there is provided a special effect that the under break is not generated and perfect blast is achieved.

Such a blast pressure-guiding control device (100 a) may be carried out with a different embodiment as shown in FIG. 8, wherein the construction of the blast pressure-blocking cover (110) is identical to that of the previous embodiment, but it is characterized in that the blast pressure-blocking cover (110) is made with such a long length that several explosives (I) can be loaded in the cover at once, not at the ratio of 1:1, and therefore the cover-assembling means (140) of the previous embodiment is omitted, and the third wall (130) of the previous embodiment is omitted, the only second wall (120) of curved surface form alone is formed integrally with the blast pressure-blocking cover (110) on the inside thereof, the plurality of buffering projections (123) are equidistantly and protrudingly formed on the outer circumferential surface of the second wall (120), and the air layers (125) are formed between the buffering projections (123).

Furthermore, a blast pressure-guiding control device (100 b) of the present invention may be also carried out with another different embodiment as shown in FIG. 9, wherein the device has very simplified structure wherein the second wall (120), third wall (130) and also cover-assembling means (140) of the first embodiment are omitted.

It has a technical construction wherein the construction of the blast pressure-blocking cover (110) is identical to that of the first embodiment, but is made with such a long length that several explosives (I) can be loaded in the cover at once, not at the ratio of 1:1. 

1. A blasting method using a blast pressure-guiding control device, wherein a blast pressure-guiding control device is provided which comprises blast pressure-blocking covers of circular cross section formed with blast pressure-guiding passage partially open on one side of the covers along the longitudinal direction thereof and with explosive-loading part inside the blast pressure-guiding passage; a second wall and third wall of curved surface form successively and integrally formed on inner side of the blast pressure-blocking covers; and cover-assembling means comprising a coupling projection protrudingly formed integrally with the second wall on one longitudinal side thereof, extending outwardly therefrom, and a coupling groove formed recessed inwardly from the second wall on the other side thereof, and wherein the blasting method comprises: explosive-loading step wherein the explosive (1) is loaded in each of a plurality of blast pressure-blocking covers formed with a blast pressure-guiding passage therein and thereafter the explosive is fixed by wrapping it with connecting bands; cover-assembling step wherein the plurality of blast pressure-blocking covers are longitudinally connected and assembled by fitting the coupling projection formed on one side of the blast pressure-blocking cover into the coupling groove of another blast pressure-blocking cover; cover-installing step wherein the plurality of connected and assembled blast pressure-blocking covers are inserted and installed in blast holes so as to face a predetermined blast line in the state of detonator leg line connected to one of the explosives being exposed to the outside of the blast hole; tamping-charging step wherein the tamping is charged in the blast holes; and detonator leg line-connecting and blasting step wherein the detonator leg line is integrally connected with blast mother line and thereafter the explosive is blasted.
 2. The blasting method using a blast pressure-guiding control device according to claim 1, wherein the detonator connected to a tip of the detonator leg line is integrally connected with the explosive of a centrally-located blast pressure-blocking cover of the plurality of connected and assembled blast pressure-blocking covers, and the detonator leg line is disposed so as to be exposed to the outside while running along a gap between inner surface of the blast pressure-blocking cover and the explosive.
 3. A blast pressure-guiding control device, comprising: blast pressure-blocking covers of circular cross section formed with blast pressure-guiding passage partially open on one side of the covers along the longitudinal direction thereof and with explosive-loading part inside the blast pressure-guiding passage; a second wall and third wall of curved surface form successively and integrally formed on inner side of the blast pressure-blocking covers; and cover-assembling means comprising a coupling projection protrudingly formed integrally with the second wall on one longitudinal side thereof, extending outwardly therefrom, and a coupling groove formed recessed inwardly from the second wall on the other side thereof.
 4. A blast pressure-guiding control device, comprising: blast pressure-blocking covers of circular cross section formed with blast pressure-guiding passage partially open on one side of the covers along the longitudinal direction thereof and with explosive-loading part inside the blast pressure-guiding passage; and a second wall of curved surface form integrally formed on inner side of the blast pressure-blocking covers.
 5. A blast pressure-guiding control device, comprising blast pressure-blocking covers of circular cross section formed with blast pressure-guiding passage partially open on one side of the covers along the longitudinal direction thereof and with explosive-loading part inside the blast pressure-guiding passage.
 6. The blast pressure-guiding control device according to claim 3, wherein a plurality of buffering projections are equidistantly and protrudingly formed on outer circumferential surface of the blast pressure-blocking cover.
 7. The blast pressure-guiding control device according to claim 3, wherein a plurality of buffering projections and are equidistantly and protrudingly formed on outer circumferential surfaces of the second wall and third wall, and air layers and are formed between the buffering projections and between the buffering projections, respectively.
 8. The blast pressure-guiding control device according to claim 4, wherein a plurality of buffering projections are equidistantly and protrudingly formed on outer circumferential surface of the second wall, and air layers are formed between the buffering projections.
 9. The blast pressure-guiding control device according to claim 3, wherein a lock with inclined surface is protrudingly formed on a tip of inner surface of the coupling projection, and the lock is fittedly coupled with a locking hole formed through the third wall while being connected with the coupling groove.
 10. The blast pressure-guiding control device according to claim 3, wherein one end portion of the plurality of connecting band for fixing the explosive by wrapping the same is integrally fixed on one side of the outer circumferential surface of the blast pressure-blocking cover, and adhesive is applied on the other end portion of the connecting bands, and an release paper is attached on a surface on which the adhesive is applied.
 11. The blast pressure-guiding control device according to claim 4, wherein a plurality of buffering projections are equidistantly and protrudingly formed on outer circumferential surface of the blast pressure-blocking cover.
 12. The blast pressure-guiding control device according to claim 5, wherein a plurality of buffering projections are equidistantly and protrudingly formed on outer circumferential surface of the blast pressure-blocking cover.
 13. The blast pressure-guiding control device according to claim 4, wherein one end portion of the plurality of connecting band for fixing the explosive by wrapping the same is integrally fixed on one side of the outer circumferential surface of the blast pressure-blocking cover, and adhesive is applied on the other end portion of the connecting bands, and an release paper is attached on a surface on which the adhesive is applied.
 14. The blast pressure-guiding control device according to claim 5, wherein one end portion of the plurality of connecting band for fixing the explosive by wrapping the same is integrally fixed on one side of the outer circumferential surface of the blast pressure-blocking cover, and adhesive is applied on the other end portion of the connecting bands, and an release paper is attached on a surface on which the adhesive is applied. 